Entomopathogenic nematodes (EPNs) of the families Heterorhabditidae and Steinernematidae are efficient biological control agents against important insect pests. In vitro liquid culture production technology is a key factor in the success of implementing EPNs as a biological control agent. One of the first steps of in vitro mass culture is to use shake flasks to obtain nematode inoculum for optimising and upscaling to desktop and industrial fermenters. This study was the first attempt on the in vitro liquid mass culture of a local South African isolate, Steinernema jeffreyense, in 250 ml Erlenmeyer flasks, together with their mutualistic bacteria, Xenorhabdus khoisanae. After the successful in vitro production of S. jeffreyense-inoculum, different parameters for optimizing infective juvenile (IJ) recovery (developmental step when the IJ moult to initiate the life cycle) and yield, were investigated. This includes the effect of the volume of liquid medium in the flasks, two different orbital shakers setups and the initial IJ inoculum density. With 30 ml of liquid medium the mean percentage recovery of IJ after six days was 86%, with a yield of 121,833 IJ ml⁻¹ after 14 days, in comparison to 75% and 99,875 IJs ml⁻¹ respectively when 50 ml of liquid medium was used. No significant difference was found between IJ recovery and yield, using different orbital shakers setups. Among the three inoculum concentrations tested (1000, 2000 and 3000 IJ ml⁻¹), the lowest concentration gave the highest IJ recovery and yield. Pathogenicity of IJs cultured in vitro was higher than those cultured in vivo.

中文翻译：

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摇瓶的体外液体培养和最优化Steinernema jeffreyense

Heterorhabditidae和Steinernematidae科的昆虫病原线虫（EPNs）是对重要害虫的有效生物防治剂。体外液体培养生产技术是成功将EPNs用作生物防治剂的关键因素。体外大规模培养的第一步之一是使用摇瓶获得线虫接种物，以优化和放大台式和工业发酵罐。这项研究是对南非本地分离株Steinernema jeffreyense以及其互生细菌Xenorhabdus khoisanae在250 ml烧瓶中进行体外液体大规模培养的首次尝试。体外成功生产后研究了用于优化感染性幼体（IJ）恢复（当IJ蜕变以启动生命周期时的发育步骤）和产量的不同参数的S. jeffreyense接种物。这包括烧瓶中液体培养基的体积，两个不同的轨道振荡器设置以及初始IJ接种物密度的影响。在使用30 ml液体培养基的情况下，六天后IJ的平均回收率为86％，在14天后产率为121,833 IJ ml ^-1，而使用50 ml液体培养基时分别为75％和99,875 IJs ml ^-1被使用了。使用不同的轨道摇床设置，IJ回收率和产量之间没有发现显着差异。在测试的三种接种物浓度中（1000、2000和3000 IJ ml ^-1），最低浓度可提供最高的IJ回收率和收率。体外培养的IJs的致病性高于体内培养的IJs。